1916 Cadillac - GM Heritage Center

40 ADJUSTMENTS
ADJUSTMENT OF CARBURETOR.
Carburetors are adjusted on cars before leaving our factory, and ordinarily
should not require re-adjusting very soon, unless perhaps to meet different
atmospheric conditions. This may be accomplished by slightly changing the
tension of the air valve spring by the adjusting screw "A."
The carburetor should not be tampered with unless it needs attention.
Before changing any carburetor adjustments, be sure that the ignition system
is in perfect order. See that the points on the spark plug are .028 in. apart.
See that the spark plug cores are clean, that the timer is properly set, that
the points are clean and in proper adjustment. Be sure that the battery
is not run down. See that all electrical connections are tight. In fact, see
that the entire ignition system is in good working order.
When it is certain that the carburetor requires adjusting, proceed as follows:
1—Open the throttle about 2 inches on the sector (at the steering wheel).
Place the spark lever in the "Driving Range" on the sector and start the
engine (See Note 1).
3—Run the engine until the water jacket on the intake pipe is hot.
3—Move the spark lever to the extreme left on the sector and the throttle
lever to a position which leaves the throttle in the carburetor slightly open.
Adjust the air valve screw "A" to a point which produces the highest engine
speed (See Note 2).
4.—Close the throttle (move it to the extreme left on the sector) and
adjust the throttle stop screw "B" to a point which causes the engine to run
at a speed of about 300 revolutions per minute. The spark lever should be at
the extreme left on the sector when this adjustment is made.
g—With the spark and throttle levers at the extreme left on the sector
adjust the air valve screw "A" to a point which produces the highest engine
speed. (See Note 2.)
C—Open the throttle until the shutter attached to the right-hand end of
the throttle shaft just covers the slot in the carburetor body. Then adjust
the screw "G" to a point which produces the highest engine speed, or to a
point where the engine slows down slightly from a "lean" mixture (See Note
2).
During very cold weather when a slightly richer mixture is desirable it
may be found best to turn the adjusting screw "G" further in a clockwise
direction.
NOTE 1.—If you crank the engine by hand, place the spark lever at the
extreme left on the sector.
NOTE 2.—Turning adjusting screws "A" or "G" in a clockwise direction
increases the proportion of gasoline to air in the mixture. Turning either in
a counter clockwise direction decrease the proportion of gasoline to air.
ADJUSTMENTS 41
PERSONAL DANGER IN RUNNING ENGINE IN CLOSED
GARAGE
Carbon monoxide, a deadly poisonous gas, is present in the exhaust of
gasoline engines. Increasing the proportion of gasoline to air in the mixture
fed to the engine, in other words, enriching it, increases the amount of carbon
monoxide given off at the exhaust pipe.
Because of the presence of carbon monoxide it is very dangerous to run
the engine for any length of time while the car is in a small, closed garage.
If the doors and windows are open the danger is very much lessened, but it
is far safer, particularly if an adjustment of the carburetor is being made, to
run the car into the open.
Serious personal injury may be caused by the presence of carbon monoxide
in a garage if the pcixentatre of it in the air is greater than a very
small fraction of one per cent. Unconsciousness may result without warning.
It is reported that no indication of danger is given by personal discomfiture
until too late. Deaths resulting from the presence of carbon monoxide in
garages have been reported.
THROTTLE PUMP.
The cylinder "C" on the carburetor bowl contains a plunger operated by
the throttle by means of the connecting rod "E."
When the throttle is opened, the plunger is forced into the gasoline in the
carburetor bowl. The plunger is drawn out of the gasoline when the throttle
is closed.
The object of the throttle pump is to force gasoline through the spraying
nozzle when the throttle is opened quickly for acceleration and to assist in
starting in extremely cold weather. (See under "To start the engine in
extremely cold weather.") When the throttle is opened slowly, the plunger
has practically no effect on the amount of gasoline passing through the spraying
nozzle.
The rod "E" is adjusted at the factory and should require no further
adjustment unless the carburetor is disassembled. In reassembling the carburetor,
the rod should be adjusted so that its upper end is flush with the
upper face of the arm "D."
TO SET CARBURETOR FLOAT.
After the carburetor has been in use for sometime, there may be a slight
amount of wear at the point of the inlet needle and its seat. If this should
occur, the height of the gasoline in the carburetor bowl will raise.
To determine if the
float is properly set. remove
the carburetor
from the engine, and
the bowl from the carburetor.
Then hold the
carburetor in the position
shown in the figure
herewith and take a
measurement from "H"
to "I." This measurement
should be }i inch.
The setting may be
corrected by bending
slightly the arm to
which the float is attached.